15M? results say the amp has issues. Either low bias or LPF filter??
20M 10W for 2 in seems? a bit low as well (I'D expect 13-15W)
At the same time the 40M results suggests maybe other things going on.
For 40M at 3W in I'd expect about 17-25W at 13.8V.? Part of the reason
is there was no intention to get flat gain from the amp.? No surprise with
a class C amp.? Hoeever if the bias is set high you do get more power
and possibly other things like spurs.
The IRF510 is performs poorly at lower voltages that why at 20V it can easily do 50W
but at 13.8 you may get around 20W.
Oddly I have an amp that uses MRF141(dual) and at 28V its easily 330W, but at 13.8V
it barely does 90W for the same drive.? THis is often seen with all Mosfets and Bipolar
devices because whne you lower votlages characteristics change.
--
Allison
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